1. Field of the Invention
The present invention relates to a digital video recorder. More specifically, the present invention relates to a digital video recorder having hierarchical memories for efficient video recording and playing back and a method for implementing hierarchical memories.
2. Description of the Related Technology
Started in the computer industry, digitalization of information has already reached its application in the telecommunications industry. Today, television broadcast signals are even digitalized. It is certain that the digitalization of television broadcast signals will open a new paradigm of two-way multimedia experience that is integrated with computer and telecommunications technologies.
Digital broadcasting is progressing around the European standard of DVD (Digital Video Broadcasting) and the American FCC standard of ATV (Advanced TV), which is in compliance with the ATSC standard, which the U.S. adopted as the next-generation TV standard to replace the conventional analog standard of NTSC.
Unlike the conventional storage of analog signals in a cassette tape, a PVR (Personal Video Recorder) receives signals, transmitted from a broadcast station or outputted from a television, converts the signals to digital information in real time, compresses the digital data into an MPEG2 file, and stores the data in a pre-installed hard disk (HD). The PVR then reads the stored data and outputs images, which are decoded in real time, to a display device.
FIG. 1 is a block diagram showing the structure of a conventional PVR system.
Referring to FIG. 1, the PVR system includes an IR receiver 110, a processor 120, a memory 130, a tuner 140, a demultiplexer 150, a decoder 160, an output unit 170, an OSD unit 180, an IDE interface 185, and a hard disk drive 190.
The IR receiver 110 receives remote control code information corresponding to a remote control operated by a user and transmits the remote control code information to the processor 120.
The processor 120 translates a remote control code received from the IR receiver 110 and transmits remote control code translation information to a corresponding device. For example, if the remote control code translation information is a command to request a channel change, the processor 120 transmits the command to the tuner 140. Likewise, if the remote control code translation information is a command to record a program, the received broadcast data is controlled to be stored in the hard disk drive 190. If the remote control code translation information is a command to request a recording list, the recording list stored in the hard disk drive 190 is outputted through the output unit 170.
The memory 130 can include a flash ROM, in which software for the operation of the PVR system is stored, and a DRAM, which stores a bitmap-type virtual screen that can be displayed through the output unit 170.
The tuner 140 receives and outputs the broadcast signals, which are selected by the control of the processor 120.
The demultiplexer 150 parses various kinds of information, such as audio, video, and other data, which are multiplexed in the broadcast signals supplied from the tuner 140.
The decoder 160 decodes audio signals, video signals, and data signals, parsed by the demultiplexer 150, and processes these signals to visual and audio information that can be outputted through the output unit 170 such that the user can recognize these signals.
The OSD unit 180 displays information corresponding to a particular command given by the processor 120. For instance, if a recording list output command is received from the processor 120, the OSD unit 180 controls the recording list extracted from the hard disk drive 190 to be displayed through the output unit 170.
The IDE interface 185 receives transport packet (TP) data, transmitted from the demultiplexer 150 for recording, and provides the TD data to the hard disk drive 190. If a playback command is received from the processor 120, the IDE interface 185 transmits the data stored in the hard disk drive 190 to the decoder 160 through the processor 120.
The hard disk drive 190 stores the TP data, transmitted from the IDE interface 185, that is, programs selected by the user through the recording command are stored in the hard disk drive 190.
It is natural that multimedia data usually have a large amount of data flow. Digital recording devices, such as the PVR, are equipped with a large capacity hard disk drive to store this large amount of data flow.
While the hard disk drive is capable of storing a large amount of data at a low cost, the hard disk drive also has its own shortcomings over the flash memories, namely, slow access speeds, slow operation speeds, low durability, and short life. The durability and life of a hard disk drive can be an important factor that determines the durability and life of a digital recording device.
As an attempt to address the above problems, the conventional digital recording device with a hard disk drive switches the hard disk drive to a stand-by mode or utilizes a large-capacity memory while the recording feature is not used. However, since most features of the digital recording device, for example, time-shift recording that can pause a live program, are based on the operation of the hard disk drive, the duration of maintaining the hard disk drive in a stand-by mode is very limited. Equipping the digital recording device with a large-capacity memory costs a lot more than the hard disk drive. Being inevitably a machine device, the hard disk drive generates a great deal of noise and heat, which can be inappropriate for an appliance.